1. Field of the Invention
The invention is directed to the roof structure of a work vehicle wherein the sound insulating foam liner together with the headliner form ventilating ducts through which airflow from a HVAC system passes.
2. Description of the Prior Art
The operator's compartment on work vehicles used in construction, agriculture mining and forestry operations is typically provided with a roll over protection system (ROPS). In addition to protecting the operator, the operator's compartment performs many other functions. The compartment must conform to various standards and regulations for operator noise comfort, visibility and interior size. As such, the operator's compartment includes sound absorbing materials to reduce noise levels in the compartment. In addition, the operator's compartment maybe provided with a heating, ventilating and air conditioning system (HVAC) to maintain a comfortable operator work environment. The HVAC system can be mounted in the roof structure of the operator's compartment. The air is routed through a series of ducts that are usually formed of molded plastic and are provided with additional insulation to reduce heat transfer from and to the air in the duct. The ducts are usually attached to each other, the HVAC unit, to the insulation and the roof structure by various mechanical mechanisms.
Typically separate components are used for sound absorption and HVAC airflow distribution functions. Sound absorption is accomplished by adhering or mechanically fastening foam sheets to either the roof or bonding them to the headliner.